Method of forming electrode with multi-dielectric layers

Abstract

A method of forming an electrode with multi-dielectric layers includes: forming a metal pattern on a substrate, in which the metal pattern includes a first metal film on the substrate and a second metal film on a top surface of the first metal film, and the first and second metal films have different metal compositions; and anodizing the metal pattern in a liquid electrolyte to form a covering anodized portion which covers an unanodized portion, in which the covering anodized portion includes a sidewall oxide dielectric structure and a top oxide dielectric structure, the sidewall oxide dielectric structure is in contact with a side surface of the unanodized portion, the top oxide dielectric structure is in contact with top surfaces of the unanodized portion and the sidewall oxide dielectric structure, and the sidewall and top oxide dielectric structures have different effective permittivities.

What is claimed is: 
     
         1 . A method of forming an electrode with multi-dielectric layers, comprising:
 forming a metal pattern on a substrate, wherein the metal pattern comprises a first metal film on the substrate and a second metal film on a top surface of the first metal film, and a metal composition of the first metal film and a metal composition of the second metal film are different; and   anodizing the metal pattern in a liquid electrolyte to form a covering anodized portion which covers an unanodized portion, wherein the covering anodized portion comprises a sidewall oxide dielectric structure and a top oxide dielectric structure, the sidewall oxide dielectric structure is in contact with a side surface of the unanodized portion, the top oxide dielectric structure is in contact with a top surface of the unanodized portion and a top surface of the sidewall oxide dielectric structure, and the sidewall oxide dielectric structure and the top oxide dielectric structure have different effective permittivities.   
     
     
         2 . The method of  claim 1 , wherein the forming the metal pattern comprises:
 depositing the first metal film on the substrate;   depositing the second metal film on the first metal film; and   performing an etching process to the first metal film and the second metal film to form the metal pattern, wherein the etching process is a photo engraving process.   
     
     
         3 . The method of  claim 1 , wherein the first metal film is a multilayer structure. 
     
     
         4 . The method of  claim 3 , wherein a bottommost layer of the first metal film contains molybdenum or titanium, and rest of the first metal film has an atomic ratio of aluminum greater than 50%. 
     
     
         5 . The method of  claim 1 , wherein the second metal film contains aluminum. 
     
     
         6 . The method of  claim 5 , wherein the second metal film is an aluminum alloy containing silicon. 
     
     
         7 . The method of  claim 5 , wherein the second metal film is an alloy containing rare earth metal. 
     
     
         8 . The method of  claim 5 , wherein the second metal film is an alloy containing alkaline earth metal. 
     
     
         9 . The method of  claim 1 , wherein a material of the second metal film comprises at least one of hafnium, tantalum, zirconium, titanium, and tungsten. 
     
     
         10 . The method of  claim 1 , further comprising:
 forming a mask pattern on a portion of a top surface of the metal pattern before the anodizing; and   removing the mask pattern after the anodizing, such that the top surface of the unanodized portion has a covered section covered by the top oxide dielectric structure and at least one uncovered section exposed by the top oxide dielectric structure.   
     
     
         11 . The method of  claim 1 , wherein the anodizing is performed to reach a termination voltage under 500 Volt. 
     
     
         12 . The method of  claim 1 , wherein the anodizing is performed at a temperature under 15° C. 
     
     
         13 . The method of  claim 1 , wherein the liquid electrolyte containing a content of water less than 20 wt %. 
     
     
         14 . The method of  claim 1 , wherein the metal pattern further comprises at least one additional metal film on a top surface of the second metal film. 
     
     
         15 . The method of  claim 14 , wherein the at least one additional metal film contains silicon. 
     
     
         16 . The method of  claim 14 , wherein the at least one additional metal film contains at least one of hafnium, tantalum, zirconium, titanium, and tungsten. 
     
     
         17 . The method of  claim 14 , wherein the at least one additional metal film contains rare earth metal. 
     
     
         18 . The method of  claim 14 , wherein the at least one additional metal film contains alkaline earth metal. 
     
     
         19 . The method of  claim 1 , further comprising:
 forming a conductive pattern across the unanodized portion through the top oxide dielectric structure.   
     
     
         20 . The method of  claim 19 , wherein the conductive pattern comprises a bottom layer and a top layer, the bottom layer is an oxide semiconductor layer, and the top layer is a metal layer. 
     
     
         21 . The method of  claim 1 , wherein a thickness of the metal pattern is less than 10 μm before the anodizing. 
     
     
         22 . The method of  claim 1 , wherein the second metal film is entirely anodized after the anodizing. 
     
     
         23 . The method of  claim 1 , wherein the second metal film is partially anodized after the anodizing. 
     
     
         24 . The method of  claim 1 , wherein the unanodized portion has an atomic ratio of aluminum greater than 50%. 
     
     
         25 . The method of  claim 1 , wherein the effective permittivity of the top oxide dielectric structure is smaller than the effective permittivity of the sidewall oxide dielectric structure. 
     
     
         26 . The method of  claim 25 , wherein the top oxide dielectric structure contains silicon oxide. 
     
     
         27 . The method of  claim 1 , wherein the effective permittivity of the top oxide dielectric structure is greater than the effective permittivity of the sidewall oxide dielectric structure.